The present disclosure relates generally to cooling of gas turbine engine components and more specifically to cooling of rotor disks in gas turbine engines.
Gas turbine engines operate by passing a volume of high energy gases through a plurality of stages of vanes and blades, each having an airfoil connected to a rotor disk, in order to drive turbines to produce rotational shaft power. The shaft power is used to drive a compressor to provide compressed air to a combustion process to generate the high energy gases. Additionally, the shaft power may be used to drive a generator for producing electricity (such as in an industrial gas turbine), or to drive a fan for producing high momentum gases for producing thrust (such as in a turbofan). In order to produce gases having sufficient energy to drive the compressor, generator and fan, it is necessary to combust the fuel at elevated temperatures and to compress the air to elevated pressures, which also increases its temperature. Thus, the vanes and blades are subjected to extremely high temperatures, often times exceeding the melting point of the alloys comprising the airfoils. High pressure turbine blades and rotor disks are subject to particularly high temperatures.
In order to maintain gas turbine engine turbine components at temperatures below their melting point, it is necessary to, among other things, cool the components with a supply of relatively cooler air, typically bled from the compressor. The cooling air can be directed into the component to provide convective cooling internally, or across the component to provide film cooling externally. For example, cooling air can be passed between turbine blade platforms and the outer diameter rim of the rotor disk to remove heat from the component, and subsequently discharged into the gas path. Various blade-to-disk attachment systems have been devised to route cooling air across the outer rim of the rotor disk. For example, U.S. Pat. No. 5,800,124, which is assigned to United Technologies Corporation, describes one system for directing cooling air to the outer rim of a rotor disk. There is a continuing need to improve cooling of turbine components to increase the temperature to which the component can be exposed, thereby increasing the overall efficiency of the gas turbine engine.